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Old 08-31-2010, 04:04 PM
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Milling BBC Heads 118cc to 99cc

Thinking about getting a set of BBC aluminum heads (procomp ovals with 118cc) for my stock flat top piston 454. I have Vortecs on their right now (99cc chamber) and I want to keep my current 9:1 CR. My question is...would it be safe to mill these heads .070" to achieve the desired 99c chamber size? Will this much milling effect the intake angel? And lastly, I'm only using a .483" lift cam but its a roller with .224 duration, and the heads have 2.300" intake valves, so will there be issues with piston to valve clearance?

I once hada set of rectangular port procomps on another low CR 454, and the piston to valve clearance was ridiculously huge. The valves barely touched the clay on top of the piston.

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Old 08-31-2010, 05:48 PM
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.070" milled is only going to get you about 10cc, you're going to need to ill nearly .125" to get to 99cc. You may want to consider angle milling, .125" flat is a ton off the head and will need different pushrods.

Milling .070" flat mill won't effect the intake angle, but may allow the intake to bottom out on the end walls of the block or cause a port mismatch. You may need to trim the ends and sides of the intake to restore correct fit. Only angle milling requires the intake angle to need correcting.

Mistake was buying flat tops in the first place in a BBC. The amount you will spend on all the milling, pushrods, time will just about pay for a new set of pistons, I would thinf that would be the smarter choice..

Only way to know about piston to valve clearance is to check it, but milling a lot and large OD valves means no one can just give you an off-hand easy answer.
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Old 08-31-2010, 08:19 PM
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I wonder if a stock flat top piston will clear a 2.3 valve.
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Old 08-31-2010, 08:36 PM
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In my opinion Flat top BBC is the best way to build one! i have a 489 running 063's and a 454 running Vortecs and want to build my spare block into a better engine for one of my boats using 100 CC aluminum heads. 100CC Edelbrocks can be had for about $660.00 each bare and that's about $400 more than a pair of Procomps however you don't have to do all the machine work. I would think a $150.00 savings buying the Procomps and milling them IF the decks are thick enough to handle it??? I Have thought about them.. Flat top.. no flame travel issues... tight quench... Easy no issue HP with no detonation issues even with the irons if you polish the combustion chamber,

All I have to say is how many RPM are you spinning that the vortecs arn't doing the job? like I say I'm running boat so 5800 RPM is huge compared to what the peanuts were pulling, easy 450 HP but if you want more tighten up the quench. 2.3" valves are killing your flow.. Everything i have researched is the stock valve size flows better than bigger because of shrouding, If you are running a roller you should be able to do remarkable things with these heads with stock valve sizes. So you might have wrecked your heads and are in the market for aluminum... Just remember savings on the purchase can be eaten up pretty fast at the machine shop and you could very well be the guinea pig in regards to deck thickness! But do post your findings!
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Old 09-01-2010, 12:48 PM
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Good call all around airboat. I'm gonna wait on the head swap and go for the edelbrocks with 100cc chambers when I do. They are about $1,000 over the procomps, but it's probably money well spent. Peanut port heads and flat top engines are much maligned by everyone it seems. Needlessly so, I think. Just look at the link below, and you'll see a peanut port that's making around 450 hp. Like I said, I'll stick with my large peanut port Vortecs for now, save up for the edelbrocks in a year or two. BTW, I regularly spin my engine to 5,750-5,950 rpm, and strangely it does not run out of breath at 4,500 rpm as people said it would.


http://www.carcraft.com/techarticles.../photo_15.html
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Old 09-01-2010, 03:47 PM
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Thats an impressive number for a peanut head. I have only flowed them once, and they flowed 220 at .400 and 220 at .700. To get 450hp from that, with low compression is impressive.
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Old 09-01-2010, 04:25 PM
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Fellas I don't mean to Hijack this thread but aren't ProComp heads any good?

450 HP with just a hair over 9:1 CR sounds good.
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Old 09-01-2010, 05:01 PM
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The Vortec's arn't Peanuts and while their flow numbers are not the greatest in the world their combustion chamber makes up for it! As far as I have herd the Procomp castings are decent however the rest of the components are not necessarily. I have herd you can build a decent head if you buy them bare and stuff them with Ferria valves and such however I have no experience with them.

I would also like to know if the ProComps could be angle milled to 100cc however like I mentioned by the time you add the machine costs you would be pretty close to bare Edelbrocks that are already angle milled to 100cc taking away the fear that the deck isn't thick enough because if it wasn't Edelbrock wouldn't sell them that way. Bare Procomps are about $400 each and the Edelbrocks are $660 each. At $260 difference I am sure there is room to angle mill them and save money?? I don't know what they would charge to angle mill that much?
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Old 09-01-2010, 05:38 PM
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Any good machine shop, the angle mill cost will eat that $250 price difference and possibly a little more. Would be at least $200 to flat mill .100".
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Old 09-01-2010, 05:48 PM
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Quote:
Originally Posted by BottleBaby
Fellas I don't mean to Hijack this thread but aren't ProComp heads any good?

450 HP with just a hair over 9:1 CR sounds good.
The Pro Comp casting is fine, as long as you aren't expecting a head to go 900hp. rocker stud bosses have been reported as breaking with really big lift(.850"+) and the springs required to go with that lift and roller cams, but otherwise just fine.

DON'T!!!!!!!!! buy them complete with ProComp parts, buy them bare so you can control the quality of parts used to complete them, the Procomp assemblys are rather shoddy cheap stuff.

You guys are easily impressed if 450 hp at 9-1 impresses you
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Old 09-01-2010, 06:35 PM
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The Vortec 454 heads are as close to PP heads as I would care to get, AFA port volume goes (~225cc-230cc by what I've read, PP heads are about 220cc)- they'll supposedly flow to 5K rpm on a 454.

They need studs to be adjustable and guides cut if the lift gets excessive. P to V clearance easily becomes an issue if the decks are cut and/or a healthy cam is used. They do have a swirl port deal going on- fine for emissions and economy but not so much for high performance, as-is.

I would prefer standard "large oval" heads (781, 049, etc.) if it was possible, BUT w/the FT pistons the 100cc aftermarket heads are the way to go, by far- again, IMO.

Good luck.
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Old 09-01-2010, 07:12 PM
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Quote:
Originally Posted by ericnova72
The Pro Comp casting is fine, as long as you aren't expecting a head to go 900hp. rocker stud bosses have been reported as breaking with really big lift(.850"+) and the springs required to go with that lift and roller cams, but otherwise just fine.

DON'T!!!!!!!!! buy them complete with ProComp parts, buy them bare so you can control the quality of parts used to complete them, the Procomp assemblys are rather shoddy cheap stuff.

You guys are easily impressed if 450 hp at 9-1 impresses you
I am. A 460 inch engine that makes 450hp and over 500ftlbs with those heads and pump gas compression, and, only costs $3000, is impressive.
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Old 09-01-2010, 07:21 PM
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Mine are for boats so under heavy load all the time for long periods of time. 450-550 HP with around 600 ft Lbs is what I'm looking for as well as bullet proof reliability. The Vortecs are working real nice on the 454 ski boat with a Comp Solid lifter flat tappet and they might go on the 489 when it gets replaced into the ski boat, expect max 5500 RPM with 063's from airboat going on 454 for a spare engine and an aluminum headed Decent squirt of NOS capable 496 for the airboat! I added ARP conversion studs instead of tapping and had to cut guides.
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Old 09-02-2010, 11:32 AM
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Quote:
Originally Posted by cobalt327
The Vortec 454 heads are as close to PP heads as I would care to get, AFA port volume goes (~225cc-230cc by what I've read, PP heads are about 220cc)- they'll supposedly flow to 5K rpm on a 454.

They need studs to be adjustable and guides cut if the lift gets excessive. P to V clearance easily becomes an issue if the decks are cut and/or a healthy cam is used. They do have a swirl port deal going on- fine for emissions and economy but not so much for high performance, as-is.

I would prefer standard "large oval" heads (781, 049, etc.) if it was possible, BUT w/the FT pistons the 100cc aftermarket heads are the way to go, by far- again, IMO.

Good luck.
airboat, I have a retraction/correction:

I earlier posted an incorrect intake port volume for peanut port heads of ~220cc. This was the AFTER porting volume of my c/n 236 heads that were used on a 468 BBC to see what they'd do, w/stock valve size and a fairly aggressive cam. The pre porting volume was ~200cc avg. between the short and long ports.

I just read that the L29 Vortec 454 heads have 233.2cc ("short" port) and 239.5cc ("long" port).

Sorry if this caused any confusion.
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